Friction clutch



E Y E G H FRICTION CLUTCH Filed April 5, 1939 /VE'I/ TEHL HAF/S OFSPEM/G Enventor 3000 4000 5000 2&2@ 33 J ff f l l k f', (Ittornegs 0 o 0.o 4 n..

Patented Mar. 11, 1941 UNITED STATES rarelvr Norrlme Harvey D. Geyer,Dayton, Ohio, assigner to General Motors Corporation, Detroit, Mich., a.corporation of Delaware Application April 3, 1939, Serial No. 265,728

4 Claims.

This invention relates to clutches and has been designed particularlyfor use as a releasable coupling between the engine shaft of the motor Afurther object is to accomplish the above i stated major object with anarrangement wherein the load on the clutch throwout mechanism decreasesin response to the movement of the throwout member and as the drivingmember decelerates.

Other objects and advantages will be undei1n stood from the descriptionwhich follows.

On the drawing: 2o Figure 1 is a transverse section, the section Figure2 is a View in elevation partly broken away.

Figure 3 is a diagram showing the results accomplished by the novelstructure.

Referring to the drawing, numeral 5 represents the engine shaft and l isa. iiywheelsecured thereto by fastening means 9. Numeral ll represents acover secured to the flywheel at I3. Within the cover is a pressureplate I5 having at Il suitable provision whereby it rotates with but mayslide axially relative to the cover. Between the pressure plate andflywheel is a driven plate I9. The driven plate is connected to a hubv2l on a driven shaft 23 by torque transmitting springs 25.

The pressure plate is urged into driving position by a coned spring disc2l. This disc engages the edge 29 of the pressure plate, the engagementforming a line contact. The cover carries a circular series of pins 3|which pins carry rings 33 and 35, one on each side of the spring plate2l' which is assembled on the pins, the pins extending through openings33 in plate 2l. From the openings there are formed in the spring plateradial slots 3l forming spring tongues 39. In the process of assemblythe coned spring is flattened between its regions of contact at 29 and33, the ring 33 thus taking the reaction when the spring acts on thepressure plate. A reciprocable throwout ring 4l is actuated by a fork,only the arms t3 of which `are shown on the drawing. Any suitable meanst5 may be used to secure the ends of the fingers to the ring 4I. Whenthe ring 4l is moved to the leit (Cl. 1ER- 135) as shown by Figure l theload is taken from the ring 33 and the spring plate is fulcrumed aboutring 35i thus removing the spring load from the pressure plate. To freethe pressure plate from the driven plate when the spring load is thus oreleased, suitable spring means such as il may be employed. Insoreleasing the clutch the spring fingers bend, thus lessening the manualeffort which would be required if the spring disc were `rigid all theway to its central opening. 10

Clutchessubstantially as above described are well known. To improve theaction thereare added, in accordance with this invention,` a set ofweights 5|. As shown, one such weight is associated with each alternatespring arm 33 and 15 the weights are positioned somewhat midway betweenthe fulcruin rings 33 and 35 and the central region of connection withthe throwout ring ll. Each weight is secured to the spring by theprovision of a narrow stem 53 which extends 20 through the spring disc`and an enlarged head 55. The center of mass of each weight is at apredetermined aXial distance marked X from the neutral axis of thespring disc. By selecting the mass of each weight and locating itscenter of 25 gravity the influence of the centrifugal force may be asdesired.

It is to be remembered that the cover, the spring assembly and thepressure plate rotate Ginny with me nywheei and engine shaft. The 30weights are therefore rotating with this assembly and exert acentrifugal force dependent upon their masses and their lever arms X. Asthe revolutions of the engine increase therefore the centrifugal forceresulting from the presence ol 35 these weights causes additional forcesto be applied through the spring 2l upon the pressure plate and acorresponding increased reaction at 33. Consequently the greater thespeed of the engine shaft the more effective is the grip upon m thedriven plate and the less is the danger of clutch slipping.

As a result of this arrangement it may be possible to reduce the weightof the spring disc. In the diagram the curve marked A shows how the 45pressure on the pressure plate increases as a result of the increase inengine speed in consequence of the presence of these weights.

The advantage of this added gripping of the driven plate might be inpart oset if the throw- 50 out mechanism required additional effort onthe part of the operator. The construction, however, not only does notrequire appreciably greater manual effort in the act of clutch releasebut the manual eiior-t during the progress of clutch relili lease isprogressively reduced. It should be observed that when the clutch is inoperation the lever arm of the weight lis X. Since, however, the arms 39are bowed in the act of clutch release, as is shown by Figure 1, thecenter of gravity of each weight is brought toward the plane of theneutral axis of the spring by the movement of the throwout mechanism.This in effect reduces the lever arm through which the Weights operate-In this way, not only does the deceleration of the engine reduce thecentrifugal force with which the weights operate but the re` duction ofthe effective lever arm reduces they effect of the rotating masses sothat if the initial pressure at the throwout mechanism is as shown bythe right end of curve B in the diagram, this pressure is veryappreciably reduced as the declutching action progresses and as theengine is allowed to decelerate. The curve B shows the progressivereduction in manual etfort required, the right end of the curveindicating the initial spring pressure to be overcome by manual effortand the left end showing the spring pressure to be resisted upon fullclutch release.

It will be evident that by the extremely simple expedient of addingthese weights to the spring arms it is possible to obtain a clutchwherein a rather light cone spring may be used and one having arelatively low spinning weight. Such a construction may be used withoutdanger of clutch slipping. In the ac-t of clutch release, the operatoris not required to maintain any considerable pressure on the throwoutmechanism. In fact the arrangement reduces the pressure required of theoperator during the progress of pedal movement and engine deceleration.

I claim:

1. In a clutch, a driving member, a spring disc rotatable therewith andprestressed to eiect clutch engagement, a plurality of weights securedto one side of said disc to increase, under the inluence of centrifugalforce, the pressure exerted by said disc.

2. In a clutch, a driving member, a spring disc rotatable therewith andprestressed to effect clutch engagement, a plurality of weights securedto one side of said disc to increase, under the inuence of centrifugalforce, the pressure exerted by said disc, together with means operableupon said spring disc to release the clutch whereby said weights areadapted to be moved toward the neutral axis of said disc to lessen theeffect of centrifugal force and reduce the eiort of clutch release.

3. In aclutch, rst and second driving members having relative axialmovements, an abutment secured to and spaced from said rst drivingmember, a driven member between said driving memb-ers, a spring discyieldingly engaging said second driving member and reacting against saidabutment, throwout means operable upon the inner margin of said springdisc, a plurality of weights mounted upon one side of said disc andlocated radially within said abutment reaction contact region.

4. The invention dei-ined by claim 3, said spring disc having radiallyextending spring lingers, said weights being attached to said Iingerswhereby the center of gravity of said weights may be moved by thethrowout mechanism toward the neutral axis oi said spring disc in theprogressive movement 0i clutch release.

HARVEY D. GEYER.

